The manufacture of man-made snow at commercial ski areas is widely practiced, as a means for not only extending the useful season of the ski area, but also improving the quality and uniformity of the surface during the primary season. Typically, in the production of man-made snow, the snow making areas are furnished with supplies of compressed air and water under pressure. Usually, these are in the form of permanent distributional installations, with provisions being made for connection of the snow making equipment at appropriate locations. The Pierce, Jr. U.S. Pat. No. 2,676,471 is representative of such an installation.
One of the common techniques for the production of man-made snow is the mixture and discharge of water and compressed air through a simple discharge gun as, for example, the type shown in the Lindlof U.S. Pat. No. 3,716,190. The water is partially atomized within the gun, when it is mixed with the high pressure compressed air, and the high velocity discharge of the water/compressed air mixture serves to complete the atomization and to convey the atomized water particles them an appropriate distance from the discharge nozzle. Snow making guns of this type are simple and reliable, but suffer a disadvantage in requiring a substantial consumption of compressed air, which is an expensive component of the snow making process.
Another common form of snow making apparatus incorporates an engine driven fan, which directs a stream of air at relatively high velocity through a confining shroud and out over the snow making area. A plurality of atomizing water nozzles are distributed around the periphery of the shroud, discharging streams of atomized water at an angle, forwardly and into the fan-driven air stream. Typically, small amounts of compressed air are injected into the water streams immediately prior to discharge from the atomizing nozzles, to facilitate the atomizing process. This technique either eliminates or greatly minimizes the requirement for a compressed air distribution system over the ski area, but in turn suffers the disadvantage that the equipment is both expensive, and inconvenient to operate. Typically, such equipment incorporates a self-contained internal combustion engine. Thus, each snow making unit requires a substantial capital investment. Moreover, the equipment is large, heavy and difficult to move easily around the snow making site. There is an additional inconvenience of having to provide constant maintenance for the internal combustion engines, as well as constant delivery of fuel, etc. Thus, although snow making equipment provided with engine-driven fans has certain significant advantages, it also has important compensating disadvantages. Illustrative of snow making equipment utilizing self-contained engine-driven fan is the Dewey U.S. Pat. No. 4,083,492.
In an effort to avoid the inconvenience and investment cost of providing internal combustion engines with each snow making unit, some of the commercially available fan-type snow making units have employed electric motors for powering the fan. While this has certain conveniences in comparison to the use of self-contained internal combustion engines, it requires the installation and maintenance of heavy-duty electrical service throughout the ski area, and also presents certain maintenance and safety problems. Accordingly, notwithstanding the apparent advantages, the use of electrically driven fans has not proven to be particularly successful commercially. Illustrative of snow making equipment utilizing electrically driven fans is the Jakob, et al. U.S. Pat. No. 3,760,598, the Hanson U.S. Pat. No. 4,004,732, and the Kircher et al. U.S. Pat. No. 4,105,161.
It has also been proposed heretofore, as for example in the Rambach U.S. Pat. No. 3,945,567, to utilize compressed air from the primary compressed air supply source to supply motive power to a fan-type snow maker. Insofar as the applicant is aware, however, such a technique has never achieved any degree of commercial success, possibly because of limitations imposed on the operation of the system by the use of compressed air as a driving medium. In this respect, the relationship of air to water in the atomizing process, for optimum results, is a variable function of temperature and humidity, particularly temperature. Thus, the utilization of compressed air as a motive source for the fan tends to impose limitations upon the flow of compressed air to the system, requiring that the pressurized water serve as the primary variable on the control of the process. This leads to significant inefficiencies in the overall operation and importantly limits the capacity of the equipment to make snow under marginal conditions.
In accordance with one of the significant aspects of the present invention, a novel and improved high efficiency, fan-type snow making apparatus is provided, which derives motive power for driving the fan from the high pressure water supply, prior to discharging of the water through snow making nozzles. In the apparatus of the invention, the snow making nozzles are of the compressed air-water type, similar in principle to the conventional snow making guns that do not use fans. In this respect, the compressed air is introduced into the water supply upstream of the nozzle discharge, enabling mixing and partial atomization to occur prior to discharge from the nozzle extremity. The atomized mixture is discharged directly into the fan-driven stream of distributional air. The arrangement provides for the making and effective widespread distribution of a high quality snow with outstanding efficiencies in terms of the consumption of high pressure compressed air from the primary source. Of course, there is energy utilization from the water supply, but this is more than offset by significant reductions in the consumption requirements for compressed air, the most expensive component of the snow making process.
In a preferred and advantageous form of the invention, all of the compressed air-water atomizing nozzles are placed directly in the fan-induced air stream, and preferably within the confines of a shroud which surrounds the fan. Accordingly, not only is the atomized air/water mixture discharged directly into the distributional air stream for better atomization and snow particle formation, but the constant bathing of the atomizing nozzles in the distributional air stream serves to keep the nozzles clean and free of ice accumulation, which can otherwise have a deleterious effect on the atomizing efficiency and effectiveness of the nozzles.